Methods and apparatus for range measurement

ABSTRACT

A first communication device determines scheduling information for a plurality of range measurement signal exchange sessions between the first communication device and one or more second communication devices, wherein the plurality of range measurement signal exchange sessions involve using at least one of i) different channel bandwidths, and ii) different physical layer data unit (PPDU) formats for the plurality of range measurement signal exchange sessions. The first communication device transmits a single packet that includes scheduling information so that a third communication device can use the scheduling information to observe one or more of the range measurement signal exchange sessions in the plurality of range measurement signal exchange sessions between the first communication device and one or more second communication devices, to determine range measurements.

CROSS REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent App. No.62/114,795, entitled “FTM Parameters and MCS Rules in Snoop Based RangeMeasurement,” filed on Feb. 11, 2015, and U.S. Provisional Patent App.No. 62/114,790, entitled “FTM Frame Filtering in Snoop Based RangeMeasurement,” filed on Feb. 11, 2015, the disclosures of which arehereby expressly incorporated herein by reference in their entireties.

Additionally, this application is related to U.S. patent applicationSer. No. 15/041,911 (now U.S. Pat. No. 10,082,557), entitled “Methodsand Apparatus for Frame Filtering in Snoop-Based Range Measurements,”filed on the same day as the present application, the disclosure ofwhich is hereby expressly incorporated herein by reference in itsentirety.

FIELD OF TECHNOLOGY

The present disclosure relates generally to wireless communicationsystems and, more particularly, to determining distances betweenwireless communication devices.

BACKGROUND

In some wireless communication systems, it may be useful to determinepositions of wireless communication devices. Some techniques fordetermining positions of wireless communication devices involvedetermining distances between communication devices, and using distancemeasurements to calculate positions of the devices. A distance betweentwo device can be determined by transmitting a signal from one device toanother, determining the time it took for the signal to travel betweenthe two devices (time of flight), and then calculating the distancebetween the two devices based on the time of flight.

SUMMARY

In an embodiment, a method includes determining, at a firstcommunication device, scheduling information for a plurality of rangemeasurement signal exchange sessions between the first communicationdevice and one or more second communication devices, wherein theplurality of range measurement signal exchange sessions involve using atleast one of i) different channel bandwidths, and ii) different physicallayer data unit (PPDU) formats for the plurality of range measurementsignal exchange sessions, and wherein the scheduling informationincludes indications of the at least one of i) the different channelbandwidths, and ii) the different PPDU formats. The method also includesgenerating, at the first communication device, a single packet thatincludes the scheduling information, and transmitting, with the firstcommunication device, the single packet so that a third communicationdevice can use the scheduling information to observe one or more of therange measurement signal exchange sessions in the plurality of rangemeasurement signal exchange sessions between the first communicationdevice and one or more second communication devices, to determine rangemeasurements.

In another embodiment, an apparatus comprises a network interface deviceassociated with a first communication device. The network interfacedevice includes one or more integrated circuits (ICs) configured to:determine scheduling information for a plurality of range measurementsignal exchange sessions between the first communication device and oneor more second communication devices, wherein the plurality of rangemeasurement signal exchange sessions involve using at least one of i)different channel bandwidths, and ii) different physical layer data unit(PPDU) formats for the plurality of range measurement signal exchangesessions, and wherein the scheduling information includes indications ofthe at least one of i) the different channel bandwidths, and ii) thedifferent PPDU formats; generate a single packet that includes thescheduling information; and cause the first communication device totransmit the single packet so that a third communication device can usethe scheduling information to observe one or more of the rangemeasurement signal exchange sessions in the plurality of rangemeasurement signal exchange sessions between the first communicationdevice and one or more second communication devices, to determine rangemeasurements.

In yet another embodiment, a method includes receiving, at a firstcommunication device, a single packet that includes schedulinginformation for a plurality of range measurement signal exchangesessions between a second communication device and one or more thirdcommunication devices, wherein the plurality of range measurement signalexchange sessions involve using at least one of i) different channelbandwidths, and ii) different physical layer data unit (PPDU) formatsfor the plurality of range measurement signal exchange sessions, andwherein the scheduling information includes indications of the at leastone of i) the different channel bandwidths, and ii) the different PPDUformats. The method also includes determining, at the firstcommunication device, when one of the range measurement signal exchangesessions will occur using the scheduling information in the singlepacket, and in response to determining when the one range measurementsignal exchange session will occur using the scheduling information inthe single packet, observing, with the first communication device, theone range measurement signal exchange session. The method furtherincludes determining, at the first communication device, rangemeasurements based on observing the one range measurement signalexchange session.

In still another embodiment, an apparatus comprises a network interfacedevice associated with a first communication device. The networkinterface device includes one or more integrated circuits (ICs)configured to: receive a single packet that includes schedulinginformation for a plurality of range measurement signal exchangesessions between a second communication device and one or more thirdcommunication devices, wherein the plurality of range measurement signalexchange sessions involve using at least one of i) different channelbandwidths, and ii) different physical layer data unit (PPDU) formatsfor the plurality of range measurement signal exchange sessions, andwherein the scheduling information includes indications of the at leastone of i) the different channel bandwidths, and ii) the different PPDUformats; determine when one of the range measurement signal exchangesessions will occur using the scheduling information in the singlepacket; in response to determining when the one range measurement signalexchange session will occur using the scheduling information in thesingle packet, observe the one range measurement signal exchangesession; and determine range measurements based on observing the onerange measurement signal exchange session.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an example system having multiple wirelesslocal area networks (WLANs), according to an embodiment.

FIG. 2A is a block diagram of an example system in which an observingstation observes range measurement signals exchanged between two accesspoints, according to an embodiment.

FIG. 2B is a signal timing diagram illustrating an example exchange ofrange measurement signals between the two access points of FIG. 2A,according to an embodiment.

FIG. 3 is a diagram of an example information element that includesscheduling information for a single range measurement session betweentwo communication devices, according to an embodiment.

FIG. 4 is a diagram of an example information element that includesscheduling information for a multiple range measurement sessions betweentwo or more communication devices, according to an embodiment.

FIG. 5 is a signal diagram that illustrates an example of a set multiplerange measurement signal exchange sessions between multiplecommunication devices, according to an embodiment.

FIG. 6 is a signal diagram that illustrates another example of a setmultiple range measurement signal exchange sessions between multiplecommunication devices, according to an embodiment.

FIG. 7 is a flow diagram of an example method for facilitatingperforming range measurements, according to an embodiment.

FIG. 8 is a flow diagram of an example method for performing rangemeasurements, according to an embodiment.

FIG. 9 is a flow diagram of another example method for facilitatingperforming range measurements, according to an embodiment.

DETAILED DESCRIPTION

Range calculation techniques described below are discussed in thecontext of wireless local area networks (WLANs) that utilize protocolsthe same as or similar to protocols defined by the 802.11 Standard fromthe Institute of Electrical and Electronics Engineers (IEEE) merely forexplanatory purposes. In other embodiments, however, range calculationtechniques are utilized in other types of wireless communicationsystems.

FIG. 1 is a block diagram of an example system including multiple WLANs10, according to an embodiment. For example, a first WLAN 10-1 includesan access point (AP) 14-1 that comprises a host processor 15 coupled toa network interface device 16. In an embodiment, the network interface16 includes one or more integrate circuits (ICs) configured to operateas discussed below. The network interface 16 includes a medium accesscontrol (MAC) processor 18 and a physical layer (PHY) processor 20. ThePHY processor 20 includes a plurality of transceivers 21, and thetransceivers 21 are coupled to a plurality of antennas 24. Althoughthree transceivers 21 and three antennas 24 are illustrated in FIG. 1,the AP 14-1 includes other suitable numbers (e.g., 1, 2, 4, 5, etc.) oftransceivers 21 and antennas 24 in other embodiments. In someembodiments, the AP 14-1 includes a higher number of antennas 24 thantransceivers 21, and antenna switching techniques are utilized. In anembodiment, the MAC processor 18 is implemented on at least a first IC,and the PHY processor 20 is implemented on at least a second IC. In anembodiment, at least a portion of the MAC processor 18 and at least aportion of the PHY processor 20 are implemented on a single IC.

The WLAN 10-1 includes a plurality of client stations 25. Although twoclient stations 25 are illustrated in FIG. 1, the WLAN 10-1 includesother suitable numbers (e.g., 1, 3, 4, 5, 6, etc.) of client stations 25in various scenarios and embodiments. The client station 25-1 includes ahost processor 26 coupled to a network interface device 27. In anembodiment, the network interface 27 includes one or more ICs configuredto operate as discussed below. The network interface 27 includes a MACprocessor 28 and a PHY processor 29. The PHY processor 29 includes aplurality of transceivers 30, and the transceivers 30 are coupled to aplurality of antennas 34. Although three transceivers 30 and threeantennas 34 are illustrated in FIG. 1, the client station 25-1 includesother suitable numbers (e.g., 1, 2, 4, 5, etc.) of transceivers 30 andantennas 34 in other embodiments. In some embodiments, the clientstation 25-1 includes a higher number of antennas 34 than transceivers30, and antenna switching techniques are utilized. In an embodiment, theMAC processor 28 is implemented on at least a first IC, and the PHYprocessor 29 is implemented on at least a second IC. In an embodiment,at least a portion of the MAC processor 28 and at least a portion of thePHY processor 29 are implemented on a single IC.

In an embodiment, the client station 25-2 has a structure that is thesame as or similar to the client station 25-1. In these embodiments, theclient station 25-2 structured the same as or similar to the clientstation 25-1 has the same or a different number of transceivers andantennas. For example, the client station 25-2 has only two transceiversand two antennas (not shown), according to an embodiment.

The system illustrated in FIG. 1 also includes a WLAN 10-2. The WLAN10-2 includes an AP 14-2 and a plurality of client stations 45. In anembodiment, the AP 14-2 has a structure that is the same as or similarto the AP 14-1. In these embodiments, the AP 14-2 structured the same asor similar to the AP 14-1 has the same or a different number oftransceivers and antennas. For example, the AP-2 has only twotransceivers and two antennas (not shown), according to an embodiment.

In an embodiment, the client stations 45 each have a respectivestructure that is the same as or similar to the client station 25-1. Inthese embodiments, each client station 45 structured the same as orsimilar to the client station 25-1 has the same or a different number oftransceivers and antennas. For example, the client station 45-1 has onlytwo transceivers and two antennas (not shown), according to anembodiment.

Although two client stations 45 are illustrated in FIG. 1, the WLAN 10-2includes other suitable numbers (e.g., 1, 3, 4, 5, 6, etc.) of clientstations 45 in various scenarios and embodiments.

In some embodiments, the AP 14-1 (AP1) exchanges range measurementsignals with the AP 14-2 (AP2) to determine a distance betweencommunication devices in the system of FIG. 1. In some embodiments, thedetermined distances between communication devices are used to determinepositions of communication devices in the system of FIG. 1, for example.In some embodiments, a client station 25, 45 (“observing station”)receives the range measurement signals exchanged between AP1 and AP2,and the time of arrival of the range measurement signals at theobserving station is utilized to determine a distance(s) between theobserving station and AP1 and/or AP2, and/or utilized to determine alocation of the observing station using a known location(s) of AP1and/or AP2.

FIG. 2A is a diagram of an example system 200 in which a first AP 204(AP1) exchanges range measurement signals with a second AP 208 (AP2),according to an embodiment. The system 200 includes a client station 212(“observing station 212”) that also receives the range measurementsignals exchanged between AP1 and AP2. Range measurement signals aresometimes referred to herein as “fine timing measurement signals” or“FTM signals”). In an embodiment, AP1 is the AP 14-1 of FIG. 1, AP2 isthe AP 14-2 of FIG. 1, and the client station 212 is the client station25-1 of FIG. 1. In other embodiments, AP1, AP2, and client station 212are wireless communication devices having different suitable structuresthan the AP 14-1, the AP 14-2, and the client station 25-1 of FIG. 1.Although only one observing station 212 is illustrated in FIG. 2A, thereare multiple observing stations in other embodiments and/or scenarios.

In some embodiments, the system 200 performs an FTM procedure in whichAP1 and AP2 exchange FTM signals while the client station 212 observesthe exchange of signals. For instance, FIG. 2B is a signal timingdiagram illustrating an example FTM procedure between AP1 and AP2, inwhich the client station 212 observes FTM signal exchanges between AP1and AP2.

AP1 generates and transmits a probe request packet 224. In response tothe probe request packet 224, AP2 generates and transmits anacknowledgment (ACK) packet 228. In an embodiment, AP2 is configured totransmit the ACK packet 228 a predetermined amount of time T_ack afterreceiving an end of the probe request packet 224. For example, acommunication protocol defines the predetermined amount of time, in anembodiment. In an embodiment, the predetermined amount of time T_ack isa short interface space (SIFS) as defined by the IEEE 802.11 Standard.In other embodiments, the predetermined amount of time T_ack is anothersuitable value. In some embodiments, AP2 transmits the ACK packet 228after an amount of time that is greater than T_ack after receiving theend of the probe request packet 224. For example, in some scenarios,processing delays in AP2 may result in AP2 transmitting the ACK packet228 after an amount of time that is greater than T_ack after receivingthe end of the probe request packet 224.

Also in response to the probe request packet 224, AP2 generates andtransmits a probe response packet 232. In response to the probe responsepacket 232, AP1 generates and transmits an ACK packet 236. In anembodiment, AP1 transmits the ACK packet 236 T_ack after an end of theprobe response packet 232 is received. In some embodiments, AP1transmits the ACK packet 236 after an amount of time that is greaterthan T_ack after receiving the end of the probe response packet 232. Forexample, in some scenarios, processing delays in AP 1 may result in AP1transmitting the ACK packet 236 after an amount of time that is greaterthan T_ack after receiving the end of the probe response packet 232.

In some embodiments, transmission of the probe request packet 224 andthe probe response packet 232 (and the corresponding ACK packets 228,236) is omitted. For example, in some embodiments, AP2 transmitsinformation included in the probe response packet 232 in beacons. Thus,if AP1 receives a beacon transmitted by AP2, AP1 does not transmit theprobe request packet 224, in some embodiments.

AP1 generates an FTM packet 240 (FTM_1). At a time t1_1, AP1 transmitsthe FTM packet 240, and AP1 records the time t1_1. In an embodiment, thetime t1_1 corresponds to an event at which a beginning of the FTM packet240 is transmitted. In an embodiment, AP1 generates the FTM packet 240to include a time stamp with the value t1_1. In other embodiments, AP1does not include a time stamp with the value t1_1 in the FTM packet 240.

At time t2_1, AP2 receives the FTM packet 240. In an embodiment, AP2records the time t2_1 at which the FTM packet 240 was received at AP2.In other embodiments, AP2 does not record the time t2_1 at which the FTMpacket 240 was received.

The observing station 212 also receives the FTM packet 240 at timet2_obs_1, and the observing station 212 records the time t2_obs_1. In anembodiment, the time t2_obs_1 corresponds to an event at which abeginning of the FTM packet 240 is received at the observing station212.

In response to the FTM packet 240, AP2 generates and transmits an ACKpacket 244. In an embodiment, AP2 transmits the ACK packet 244 at a timet3_1. In an embodiment, time t3_1 corresponds to t2_1+T_ack. In anembodiment, AP2 records the time t3_1 at which AP2 transmits the ACKpacket 244. In other embodiments, AP2 does not record the time t3_1. Insome embodiments, t3_1 is greater than t2_1+T_ack. For example, in somescenarios, processing delays in AP2 may result in t3_1 being greaterthan t2_1+T_ack.

At time t4_1, AP1 receives the ACK packet 244. In an embodiment, AP1records the time t4_1 at which AP 1 receives the ACK packet 244. In anembodiment, the time t4_1 corresponds to an event at which a beginningof the ACK packet 244 is received at AP1.

The observing station 212 also receives the ACK packet 244 at timet4_obs_1, and the observing station 212 records the time t4_obs_1. In anembodiment, the time t4_obs_1 corresponds to an event at which abeginning of the ACK packet 244 is received at the observing station212.

Transmission of an FTM packet and a responsive ACK packet (e.g., the FTMpacket 240 and the responsive ACK packet 244) is sometimes referred toherein as an FTM exchange. Thus, the FTM packet 240 and the responsiveACK packet 244 correspond to one FTM exchange. In some embodiments, anFTM signal exchange procedure comprises multiple FTM exchanges.

For instance, FIG. 2B illustrates three FTM signal exchanges. Inparticular, as part of a second FTM exchange, AP1 generates an FTMpacket 248 (FTM_2). At a time t1_2, AP1 transmits the FTM packet 248,and AP1 records the time t1_2. In an embodiment, the time t1_2corresponds to an event at which a beginning of the FTM packet 248 istransmitted. In an embodiment, AP1 generates the FTM packet 248 toinclude a time stamp with the value t1_2. In other embodiments, AP1 doesnot include a time stamp with the value t1_2 in the FTM packet 248. Inan embodiment, AP1 generates the FTM packet 248 to include times t1_1and t4_1, e.g., in a PHY payload portion of the FTM packet 248.

At time t2_2, AP2 receives the FTM packet 248. In an embodiment, AP2records the time t2_2 at which the FTM packet 248 was received at AP2.In other embodiments, AP2 does not record the time t2_2 at which the FTMpacket 248 was received.

The observing station 212 also receives the FTM packet 248 at timet2_obs_2, and the observing station 212 records the time t2_obs_2. In anembodiment, the time t2_obs_2 corresponds to an event at which abeginning of the FTM packet 248 is received at the observing station212. As discussed above, in an embodiment, the FTM packet 248 includestimes t1_1 and t4_1, e.g., in a PHY payload portion of the FTM packet248. Thus, in an embodiment, the observing station 212 records the timest1_1 and t4_1 that were included in the FTM packet 248.

In response to the FTM packet 248, AP2 generates and transmits an ACKpacket 252. In an embodiment, AP2 transmits the ACK packet 252 at a timet3_2. In an embodiment, time t3_2 corresponds to t2_2+T_ack. In anembodiment, AP2 records the time t3_2 at which AP2 transmits the ACKpacket 252. In other embodiments, AP2 does not record the time t3_2. Insome embodiments, t3_2 is greater than t2_2+T_ack. For example, in somescenarios, processing delays in AP2 may result in t3_2 being greaterthan t2_2+T_ack.

At time t4_2, AP1 receives the ACK packet 252. In an embodiment, AP1records the time t4_2 at which AP1 receives the ACK packet 252. In anembodiment, the time t4_2 corresponds to an event at which a beginningof the ACK packet 252 is received at AP1.

The observing station 212 also receives the ACK packet 252 at timet4_obs_2, and the observing station 212 records the time t4_obs_2. In anembodiment, the time t4_obs_2 corresponds to an event at which abeginning of the ACK packet 252 is received at the observing station212.

As part of a third FTM exchange, AP1 generates an FTM packet 256(FTM_3). At a time t1_3, AP1 transmits the FTM packet 256, and AP1records the time t1_3. In an embodiment, the time t1_3 corresponds to anevent at which a beginning of the FTM packet 256 is transmitted. In anembodiment, AP1 generates the FTM packet 256 to include a time stampwith the value t1_3. In other embodiments, AP1 does not include a timestamp with the value t1_3 in the FTM packet 256. In an embodiment, AP1generates the FTM packet 256 to include times t1_2 and t4_2, e.g., in aPHY payload portion of the FTM packet 256.

At time t2_3, AP2 receives the FTM packet 256. In an embodiment, AP2records the time t2_3 at which the FTM packet 256 was received at AP2.In other embodiments, AP2 does not record the time t2_3 at which the FTMpacket 256 was received.

The observing station 212 also receives the FTM packet 256 at timet2_obs_3, and the observing station 212 records the time t2_obs_3. In anembodiment, the time t2_obs_3 corresponds to an event at which abeginning of the FTM packet 256 is received at the observing station212. As discussed above, in an embodiment, the FTM packet 256 includestimes t1_2 and t4_2, e.g., in a PHY payload portion of the FTM packet256. Thus, in an embodiment, the observing station 212 records the timest1_2 and t4_2 that were included in the FTM packet 256.

In response to the FTM packet 256, AP2 generates and transmits an ACKpacket 260. In an embodiment, AP2 transmits the ACK packet 260 at a timet3_3. In an embodiment, time t3_3 corresponds to t2_3+T_ack. In anembodiment, AP2 records the time t3_3 at which AP2 transmits the ACKpacket 260. In other embodiments, AP2 does not record the time t3_3. Insome embodiments, t3_3 is greater than t2_3+T_ack. For example, in somescenarios, processing delays in AP2 may result in t3_3 being greaterthan t2_3+T_ack.

At time t4_3, AP1 receives the ACK packet 260. In an embodiment, AP1records the time t4_3 at which AP1 receives the ACK packet 260. In anembodiment, the time t4_3 corresponds to an event at which a beginningof the ACK packet 260 is received at AP 1.

The observing station 212 also receives the ACK packet 260 at timet4_obs_3, and the observing station 212 records the time t4_obs_3. In anembodiment, the time t4_obs_3 corresponds to an event at which abeginning of the ACK packet 260 is received at the observing station212.

A group of FTM exchanges is referred to herein as an FTM burst. Forexample, an FTM burst 270 includes the three FTM exchanges associatedwith FTM_1, FTM_2, and FTM_3. As will be describe in more detail below,in an embodiment, an FTM burst may include other suitable number of FTMexchanges, such as one, two, four, five, six, etc.

A location of the observing station 212 can be determined in part with adifferential distance D_(SR) between the observing station 212 and eachof AP1 and AP2, whereD _(SR) =c×(T _(SO) −T _(RO))  Equation 1where c is the speed of light, T_(SO) is a time of flight between AP1and the observing station 212, and T_(RO) is a time of flight betweenAP2 and the observing station 212. In some embodiments, a location ofthe observing station 212 can be determined using i) D_(SR), and ii) a)a known location of AP1, and/or b) a known location of AP2.

In an embodiment, the differential distance D_(SR) between the observingstation 212 and each of AP1 and AP2 can be calculated asD _(SR) =c×(t4_obs−t2_obs−T−(t4−t1))  Equation 2where t4_obs is one of t4_obs_1, t4_obs_2, and t4_obs_3; t2_obs is oneof t2_obs_1, t2_obs_2, and t2_obs_3; t4 is one of t4_1, t4_2, and t4_3;t1 is one of t1_1, t1_2, and t1_3; and T is a time of flight of a lineof sight transmission from AP1 to AP2. In an embodiment, T is calculatedasT=t4−t 1−T_ack  Equation 3In other embodiments, T is calculated asT=t2−t1  Equation 4where t2 is one of t2_1, t2_2, and t2_3. In another embodiment, when thelocations of AP1 and AP2 are known, T is calculated by dividing thedistance between AP1 and AP2 by the speed of light c.

In various embodiments, D_(SR), is calculated at one or more of AP1,AP2, the observing station 212, or another suitable device (not shown inFIG. 2A). Thus, in various embodiments, time values and other parameters(if any) necessary for calculating D_(SR) are sent to the devicecalculating the D_(SR) (the “calculating device”) if the calculatingdevice does not already have the time values/parameters.

As shown in the example of FIG. 2B, AP2 merely responds to FTM packetsfrom AP1 with ACKs. Thus, in some embodiments, AP2 is not configured totransmit FTM signals and/or initiate FTM exchanges. For example, in anembodiment, the AP2 is a legacy device that is configured to support anolder communication protocol (e.g., IEEE 802.11a), whereas FTM exchangesare defined by a more recent communication protocol that is backwardcompatible with the older communication protocol. Thus, for example, AP2responds to FTM packets from AP1 with ACKs but may not be able tounderstand all of the contents of the FTM packets. In other embodiments,however, AP2 is able to understand all of the contents of the FTMpackets from AP1.

In some embodiments, the communication protocol utilized by AP1, AP2,and the observing station 212 defines, for a particular PPDU format,mandatory i) rates, ii) modulation and coding schemes (MCSs), iii)numbers of spatial streams, and/or iv) mandatory combinations of a) MCSsand b) numbers of spatial streams, that must be supported by allcommunication devices. In some embodiments, the AP1 is restricted tousing, when transmitting FTM packets according to a particular PPDUformat, one or more of i) a mandatory rate, ii) a mandatory MCS, and/oriii) a mandatory combination of a) an MCS, and b) a number of spatialstreams, for the particular PPDU format, as specified by thecommunication protocol (even if channel conditions and capabilities ofAP2 would allow using a higher rate, a higher MCS, and/or a highernumber of spatial streams). Using a mandatory rate, a mandatory MCS,and/or a mandatory number of spatial streams for the FTM transmissionsincreases the probability that the observing station 212 will correctlyreceive the FTM packets from AP 1 and the ACKs from AP2.

To facilitate the observing station 212 in observing FTM exchangesbetween AP1 and AP2, AP1 may transmit FTM scheduling information to theobserving station 212, where the FTM scheduling information providesinformation regarding when the FTM burst 270 will occur. In someembodiments, AP1 transmits FTM scheduling information in one or morebeacon frames, and the observing station 212 obtains the FTM schedulinginformation from the one or more beacon frames. In some embodiments, AP1transmits FTM scheduling information in one or more broadcast packets,and the observing station 212 obtains the FTM scheduling informationfrom the one or more broadcast packets. In some embodiments, theobserving station 212 transmits a request packet to AP1, the requestpacket including information that prompts AP1 to transmit FTM schedulinginformation in one or more FTM response packets to the observing station212. The observing station 212 obtains the FTM scheduling informationfrom the one or more FTM response packets, in some embodiments.

Observing, by a first communication device, of FTM packet exchangesbetween a second communication device and a third communication devicefor range measurement purposes, such as discussed above in connectionwith FIGS. 2A and 2B, is sometimes referred to as “snoop-based rangemeasurement.”

FIG. 3 is a diagram of an example information element (IE) 300 that isutilized by a first communication device to provide FTM schedulinginformation to a second communication device in preparation for an FTMexchange between the first communication device and the secondcommunication device. The IE 300 includes an element identifier (ID)field 304 having a value indicating that the IE 300 corresponds to FTMscheduling information. The IE 300 also includes a length field 308 thatincludes a value indicating a length of the IE 300. The IE 300 alsoincludes an FTM parameter field 312 for including FTM informationregarding a single FTM session.

For example, the FTM parameter field 312 includes a number of burstsexponent field 332 that specifies an exponent value exp corresponding toa number of FTM bursts in the FTM session specified by 2^exp.

A burst timeout field 336 specifies a duration of each burst in the FTMsession.

A minimum delta FTM field 340 specifies a minimum time betweenconsecutive FTM packets (e.g., measured from a start of an FTM packet toa start of a next FTM packet) within a burst.

A partial TSF timer field 344 indicates a time when the first burst ofthe FTM session starts.

An FTMs per burst field 360 specifies a number of FTM packets in eachFTM burst.

An FTM channel spacing/format field 368 specifies information regardingthe channel via which FTM packets will be transmitted and a PHY protocoldata unit (PPDU) format that will be used during the FTM session. Forexample, in an illustrative embodiment, the field 368 specifiesinformation such as a channel bandwidth to be used, a PPDU format (e.g.,IEEE 802.1 in, IEEE 802.11ac, etc.), etc.

A burst period field 372 specifies an interval between two bursts in theFTM session.

In some embodiments and/or scenarios, communication devices in acommunication system have different capabilities with regard to channelbandwidths, modulation and coding schemes (MCSs), PPDU formats, etc. Forexample, some wireless communication protocols define different versionsof the protocol, where more recent versions generally specify morecapabilities (e.g., wider channel bandwidths, higher MCSs providinghigher throughputs, etc.) as compared to older versions, but where themore recent versions are backward compatible with the older versions.For instance, with the IEEE 802.11 Standard, the most recent IEEE802.11ac Standard permits channel bandwidths of 20 MHz, 40 MHz, 80 MHz,and 160 MHz; the IEEE 802.11n Standard permits channel bandwidths ofonly 20 MHz and 40 MHz; and the older IEEE 802.11a Standard permits onlya channel bandwidth of only 20 MHz. Additionally, the IEEE 802.11acStandard provides higher MCSs than both the IEEE 802.11n Standard andthe IEEE 802.11a Standard; and the IEEE 802.11n Standard provides higherMCSs than the IEEE 802.11a Standard. Also, the IEEE 802.11ac Standarddefines a different PPDU format (sometimes referred to as a very highthroughput (VHT) PPDU format) than both the IEEE 802.11n Standard andthe IEEE 802.11 a Standard; and the IEEE 802.11n Standard defines adifferent PPDU format (sometimes referred to as a high throughput (HT)PPDU format) than the format defined by the IEEE 802.11a Standard(sometimes referred to as a legacy PPDU format).

Thus, in some embodiments and/or scenarios, when AP1 transmits an FTMburst to AP2 using a set of transmission characteristics including i) achannel bandwidth, ii) a PPDU format, and iii) an MCS, where the set oftransmission characteristics is supported by a first set of one or moreclient device but is not supported by a second set of one or more clientdevices, the second set of one or more client devices will not be ableto observe the FTM burst for snoop-based range measurements.

In some embodiments, AP1 schedules multiple FTM sessions with AP2 tofacilitate snoop-based range measurements by multiple client deviceshaving different communication capabilities, where each session uses adifferent set of transmission characteristics (e.g., one or more of i) adifferent channel bandwidth, ii) a different PPDU format, and/or iii) adifferent MCS). In some embodiments, AP1 schedules multiple FTM sessionswith multiple other APs to facilitate snoop-based range measurements bymultiple client devices, where different sessions may use a same ordifferent set of transmission characteristics (e.g., one or more of i) adifferent channel bandwidth, ii) a different PPDU format, and/or iii) adifferent MCS).

FIG. 4 is a diagram of an example IE 400 that is utilized by an AP toprovide FTM scheduling information to one or more client stations inpreparation for snoop-based range measurements, according to anembodiment. The IE 400 includes an element ID field 404 having a valueindicating that the IE 400 corresponds to FTM scheduling information forsnoop-based range measurements. The IE 400 also includes a length field408 that includes a value indicating a length of the IE 400. The IE 400also includes a snoop-based FTM range measurement parameter field 412for including FTM information regarding one or more FTM sessions withone or more other APs for purposes of snoop-based range measurements.

For example, the field 412 includes one or more snoop-based FTM rangemeasurement parameter fields 416, where each field 416 specifies FTMsession parameters corresponding to a single respective peer AP. Forinstance, FIG. 5 illustrates an AP1 performing FTM packet exchanges witha peer AP2 and a peer AP3. Thus, in an embodiment, a first field 416-1specifies FTM session parameters for FTM packet exchanges with AP2, anda second field 416-2 specifies FTM session parameters for FTM packetexchanges with AP3, according to an embodiment.

Each field 416 specifies FTM session parameters for one or more FTMsessions with a single respective peer AP. For example, FIG. 5illustrates multiple AP1 FTM sessions with the peer AP2 (e.g., a firstFTM session and a second FTM session). Thus, in an embodiment, the firstfield 416-1 specifies parameters for the first FTM session with AP2, aswell as parameters for the second FTM session with AP2, according to anembodiment.

In an embodiment, each field 416 includes a first portion 420 havingparameters that are common to the one or more FTM sessions correspondingto the field 416, and a second portion 424 having parameters that arespecific to a first FTM session. If the field 416 includes parametersfor multiple FTM sessions, the field includes one or more third portions428 having parameters that are specific to one or more respectiveadditional FTM sessions, according to an embodiment.

The portion 420 includes a peer basic service set identifier (BSSID)field 440 that specifies a BSSID of the peer AP to which AP1 willtransmit FTM bursts. For instance, in the example illustrated in FIG. 5,the peer BSSID field 440 includes a BSSID of AP2, according to anembodiment.

The portion 420 also includes a primary channel field 444 that specifiesa primary channel corresponding to each FTM session corresponding to thefield 416. In some embodiments, the primary channel has a bandwidth of20 MHz. In some embodiments in which the primary channel has a bandwidthof 20 MHz and the channel bandwidth is larger than 20 MHz, a clientstation can identify the channel in which the FTM session will occurbased on knowledge of the primary channel along with knowledge of thechannel bandwidth (specified in another field as discussed below). Forexample, in an embodiment, the client station can identify the channelin which the FTM session will occur based on the primary channel and thechannel bandwidth using channelization rules specified by acommunication protocol.

In some embodiments, at least some communication devices in the systemare capable of transmitting via a communication channel that is notcontiguous in frequency (e.g., the communication channel includesmultiple segments (in frequency) including a first segment (segment 0)and a second segment (segment 1), where segment 0 and segment 1 areseparated in frequency). When the communication channel is notcontiguous in frequency and includes multiple segments, the primarychannel field 444 specifies a primary channel within segment 0,according to an embodiment. In some embodiments, a client station canidentify segment 0 based on knowledge of the primary channel along withknowledge of the channel bandwidth and/or knowledge of a format of thechannel, e.g., that the channel is not contiguous in frequency(specified in another field as discussed below). For example, in anembodiment, the client station can identify segment 0 based on theprimary channel and that the channel has a noncontiguous bandwidth of160 MHz using channelization rules specified by a communicationprotocol.

A burst timeout field 448 specifies a duration of each burst in each FTMsession corresponding to the field 416.

An FTMs per burst field 452 specifies a number of FTM packets in eachFTM burst in each FTM session corresponding to the field 416.

A minimum delta FTM field 456 specifies a minimum time betweenconsecutive FTM packets (e.g., measured from a start of an FTM packet toa start of a next FTM packet) within each burst in each FTM sessioncorresponding to the field 416.

A burst period field 460 specifies an interval between two bursts ineach FTM session corresponding to the field 416.

The portion 424 specifying parameters for the first FTM session includesa partial TSF timer field 464 that indicates a time when the first burstof the first FTM session starts.

An FTM channel spacing/format field 468 specifies information regardingthe channel via which FTM packets will be transmitted and a PPDU formatthat will be used during the FTM session. For example, in anillustrative embodiment, the field 468 specifies information such as achannel bandwidth to be used, a PPDU format (e.g., IEEE 802.1 in, IEEE802.11ac, etc.), etc. In an embodiment, the FTM channel spacing/formatfield 468 specifies whether the channel bandwidth is 20 MHz, 40 MHz, 80MHz, 160 MHz, contiguous, or 160 MHz, noncontiguous, (e.g., a first 80MHz segment (segment 0) and a second 80 MHz segment (segment 1), wheresegment 0 and segment 1 are separated in frequency). In otherembodiments, other suitable channel bandwidths are utilized, and thusthe FTM channel spacing/format field 468 specifies another suitablechannel bandwidth.

In an embodiment, the FTM channel spacing/format field 468 specifieswhether an HT PPDU format will be utilized or a VHT PPDU format will beutilized. In other embodiments, other suitable PPDU formats areutilized, and thus the FTM channel spacing/format field 468 specifiesanother suitable PPDU format.

A field 472 indicates whether the field 416 includes FTM schedulinginformation for another FTM session with the same peer AP. For example,when a first value of the field 472 indicates that there is no furtherFTM scheduling information for another FTM session with the same peerAP, the portion(s) 428 are omitted from the field 416, according to anembodiment. As another example, when a second value of the field 472indicates that there is further FTM scheduling information for one ormore further FTM sessions with the same peer AP, one or more portions428 are included in the field 416, according to an embodiment.

A channel center segment 1 field 476 specifies information indicating acenter frequency of a segment 1 of an 80+80 MHz communication channel.

When included, the portion(s) 428 specify parameters for one or moreadditional FTM sessions. In an embodiment, each portion 428 includes thesame fields as the portion 424, but specifying parameters for the one ormore additional FTM sessions.

Although FIG. 4 illustrates fields having certain lengths arranged in acertain order, FIG. 4 is merely an example, and fields have othersuitable lengths and positions in other embodiments. In someembodiments, one or more of the fields illustrated in FIG. 4 areomitted. For example, in some embodiments, the peer BSSID field 440 isomitted. For instance, in some embodiments, observing stations identifyFTM packets of interest based on a source address or identifier(sometimes referred to as a “transmitter address” or “transmitter ID”)in the FTM packets, and thus the observing stations do not need to knowthe recipient of the FTM packets. As another example, one or morereserved fields (Rsvd.) in FIG. 4 are omitted, have different sizes,etc. In some embodiments, one or more of other fields not illustrated inFIG. 4 are included in the IE 400.

Thus, in some embodiments, an AP provides FTM scheduling information ina single IE (such as the IE 400 of FIG. 4 or another suitable IE) formultiple FTM sessions with one or more other APs for purposes ofsnoop-based range measurements. In some embodiments, an AP includes thesingle IE (with FTM scheduling information for multiple FTM sessionswith one or more other APs) in a beacon frame. In some embodiment, an APincludes the single IE (with FTM scheduling information for multiple FTMsessions with one or more other APs) in a broadcast frame. In someembodiment, an AP includes the single IE (with FTM schedulinginformation for multiple FTM sessions with one or more other APs) in anFTM response packet sent by the AP in response to an FTM request packetfrom an observing client station. Thus, in various embodiments, an APincludes FTM scheduling information for multiple FTM sessions with oneor more other APs in a single beacon frame, in a single broadcastpacket, in a single FTM response packet, etc.

FIG. 5 illustrates a set 500 of multiple FTM sessions with multiple APsas an illustrative example. In an embodiment, scheduling information forthe set 500 is included in a single IE (such as the IE 400 of FIG. 4 oranother suitable IE). In some embodiments, scheduling information forthe set 500 is included in a single beacon frame, a single broadcastpacket, a single FTM response packet, etc.

The set 500 includes a first FTM session 504 between a first AP (AP1)and a second AP (AP2). The set 500 also includes a second FTM session508 between AP1 and AP2. The set 500 also includes a third FTM session512 between AP1 and a third AP (AP3).

The first FTM session 504 includes a first burst 520-1, a second burst520-2, and a third burst 520-3. The second FTM session 508 includes afirst burst 524-1, a second burst 524-2, and a third burst 524-3. Thethird FTM session 512 includes a first burst 528-1 and a second burst528-2.

Referring to FIGS. 4 and 5, a BSSID of AP2 is specified in field 440within a first field 416-1, according to an embodiment. In someembodiments, however, the field 440 is omitted and the IE 400 does notspecify a BSSID of AP2. A primary channel corresponding to the first FTMsession 504 and the second FTM session is specified in field 444 withinthe first field 416-1, according to an embodiment. A duration of eachburst 520, 524 is specified in the field 448 within the first field416-1, according to an embodiment. A number of FTM packets in each burst520, 524 is specified in the field 452 within the first field 416-1,according to an embodiment. A minimum time between consecutive FTMpackets each burst 520, 524 is specified in the field 456 within thefirst field 416-1, according to an embodiment. A burst period for burstsessions 504 and 508 is specified in the field 460 within the firstfield 416-1, according to an embodiment.

A time at which burst 520-1 begins in indicated by the field 464 withinthe first field 416-1, according to an embodiment. A channel bandwidthcorresponding to the first FTM session 504 is indicated by the field 468within the first field 416-1, according to an embodiment. Additionally,the field 468 within the first field 416-1 indicates that FTM packets inthe first FTM session 504 have an HT PPDU format, according to anembodiment.

The field 472 in the first field 416-1 is set to a first value thatindicates there is another FTM session with AP2, and thus the firstfield 416-1 includes the portion 428. A time at which burst 524-1 beginsin indicated by the partial TSF timer field in the portion 428 withinthe first field 416-1, according to an embodiment. A channel bandwidthcorresponding to the second FTM session 508 is indicated by the FTMchannel spacing/format field in the portion 428 within the first field416-1, according to an embodiment. Additionally, the FTM channelspacing/format field in the portion 428 within the first field 416-1indicates that FTM packets in the second FTM session 508 have a VHT PPDUformat, according to an embodiment. The “more sessions with same AP”field in the portion 428 within the first field 416-1 is set to a secondvalue that indicates there is not another FTM session with AP2, and thusthe first field 416-1 does not include any further portions 428.

A BSSID of AP3 is specified in field 440 within a second field 416-2,according to an embodiment. In some embodiments, however, the field 440is omitted and the IE 400 does not specify a BSSID of AP3. A primarychannel corresponding to the third FTM session 512 is specified in field444 within the second field 416-2, according to an embodiment. Aduration of each burst 528 is specified in the field 448 within thesecond field 416-2, according to an embodiment. A number of FTM packetsin each burst 528 is specified in the field 452 within the second field416-2, according to an embodiment. A minimum time between consecutiveFTM packets each burst 528 is specified in the field 456 within thesecond field 416-2, according to an embodiment. A burst period for burstsession 512 is specified in the field 460 within the second field 416-2,according to an embodiment.

A time at which burst 528-1 begins in indicated by the field 464 withinthe second field 416-2, according to an embodiment. A channel bandwidthcorresponding to the third FTM session 512 is indicated by the field 468within the second field 416-2, according to an embodiment. Additionally,the field 468 within the second field 416-2 indicates that FTM packetsin the third FTM session 512 have a VHT PPDU format, according to anembodiment. The field 472 in the second field 416-2 is set to the secondvalue that indicates there is not another FTM session with AP3, and thusthe field 416-2 does not include any portions 428.

In some embodiments, different burst periods are scheduled for differentFTM sessions with a single peer AP. Thus, in some embodiments, the field416 includes respective burst period fields (similar to the burst periodfield 460 of FIG. 4) for respective FTM sessions with a single peer AP.

FIG. 6 illustrates a set 600 of multiple FTM sessions with a single peerAP as an illustrative example. In an embodiment, scheduling informationfor the set 600 is included in a single IE (such as an IE similar to theIE 400 of FIG. 4 or another suitable IE). In some embodiments,scheduling information for the set 600 is included in a single beaconframe, a single broadcast packet, a single FTM response packet, etc.

The set 600 includes a first FTM session 604 between a first AP (AP1)and a second AP (AP2). The set 600 also includes a second FTM session608 between AP1 and AP2.

The first FTM session 604 includes a first burst 620-1, a second burst620-2, and a third burst 620-3. The second FTM session 608 includes afirst burst 624-1 and a second burst 524-2.

Referring to FIGS. 4 and 6, a BSSID of AP2 is specified in field 440,according to an embodiment. In some embodiments, however, the field 440is omitted and the IE 400 does not specify a BSSID of AP2. A primarychannel corresponding to the first FTM session 604 and the second FTMsession 608 is specified in field 444, according to an embodiment. Aduration of each burst 620, 624 is specified in the field 448, accordingto an embodiment. A number of FTM packets in each burst 620, 624 isspecified in the field 452, according to an embodiment. A minimum timebetween consecutive FTM packets each burst 620, 624 is specified in thefield 456, according to an embodiment.

A burst period 630 for burst session 604 is specified in the field 460,according to an embodiment. A time at which burst 620-1 begins inindicated by the field 464, according to an embodiment. A channelbandwidth corresponding to the first FTM session 604 is indicated by thefield 468, according to an embodiment. Additionally, the field 468indicates that FTM packets in the first FTM session 504 have an HT PPDUformat, according to an embodiment.

The field 472 is set to a first value that indicates there is anotherFTM session with AP2, and thus the first field 416-1 includes theportion 428.

A burst period 640 for burst session 608 is specified in a burst periodfield (not shown) in the portion 428, according to an embodiment. A timeat which burst 624-1 begins in indicated by the partial TSF timer fieldin the portion 428, according to an embodiment. A channel bandwidthcorresponding to the second FTM session 608 is indicated by the FTMchannel spacing/format field in the portion 428, according to anembodiment. Additionally, the FTM channel spacing/format field in theportion 428 indicates that FTM packets in the second FTM session 608have a VHT PPDU format, according to an embodiment. The “more sessionswith same AP” field in the portion 428 is set to a second value thatindicates there is not another FTM session with AP2, and thus the firstfield 416-1 does not include any further portions 428.

Referring again to FIG. 4, in some embodiments, one or more fields inthe common parameters portion 420 are instead included in the portions424 and 428 so that other parameters can be made different for differentburst sessions with the same peer AP. For example, in variousembodiments, various suitable combinations of one or more of thefollowing parameters can be made different for different burst sessionswith the same peer AP: burst timeout, FTMs per burst, minimum delta FTM,burst period, etc. Similarly, in some embodiments, one or more fields inthe portions 424 and 428 are instead included in the portion 420 so thatother parameters are made common for different burst sessions with thesame peer AP. For instance, in various embodiments, various suitablecombinations of one or more of the following parameters are made thecommon for different burst sessions with the same peer AP: channelbandwidth, PPDU format, etc.

Referring again to FIGS. 2A and 2B, in some embodiments, a communicationprotocol according to which AP 1 and AP2 communicate generally permitsAP 1 and AP2 to exchange packets formatted according to a combination ofi) a rate, ii) an MCS, iii) a number of spatial streams, and iv) achannel bandwidth, that is supported by both AP1 and AP2. But in somescenarios, the combination supported by both AP1 and AP2 is notsupported by the observing station 212.

In some embodiments, the communication protocol utilized by AP1, AP2,and the observing station 212 defines, for a particular PPDU format,mandatory i) rates, ii) MCSs, iii) numbers of spatial streams, and/oriv) mandatory combinations of a) MCSs and b) numbers of spatial streams,that must be supported by all communication devices.

Thus, in some embodiments, the AP1 is restricted to using, whentransmitting FTM packets according to a particular PPDU format, one ormore of i) a mandatory rate, ii) a mandatory MCS, and/or iii) amandatory combination of a) an MCS, and b) a number of spatial streams,for the particular PPDU format, as specified by the communicationprotocol.

FIG. 7 is a flow diagram of an example method 700 for facilitatingperformance of range measurements in a wireless communication network,according to an embodiment. In some embodiments, the network interfacedevice 16 of FIG. 1 is configured to implement the method 700, andmerely for ease of explanation, the method 700 is described withreference to FIGS. 1, 2A, 2B, and 4. However, the method 700 is utilizedwith and/or implemented in suitable systems, devices, and/or dataformats other than those discussed in connection with in FIGS. 1, 2A,2B, and 4, in some embodiments.

At block 704, scheduling information for a plurality of rangemeasurement signal exchange sessions are determined, the plurality ofrange measurement signal exchange sessions involving transmission ofrange measurement signals from a first communication device to one ormore second communication devices. For example, in an embodiment,scheduling information for a plurality of FTM signal exchange sessionsare determined. In some embodiments, the plurality of range measurementsignal exchange sessions include a first range measurement signalexchange session that utilizes a first channel bandwidth, and a secondrange measurement signal exchange session that utilizes a second channelbandwidth different than the first channel bandwidth. In someembodiments, the first range measurement signal exchange session isbetween the first communication device and one second communicationdevice, and the second range measurement signal exchange session is alsobetween the first communication device and the one second communicationdevice. In some embodiments, the first range measurement signal exchangesession is between the first communication device and one secondcommunication device, and the second range measurement signal exchangesession is between the first communication device and another secondcommunication device.

In some embodiments, the plurality of range measurement signal exchangesessions include a first range measurement signal exchange session thatutilizes a first PPDU format, and a second range measurement signalexchange session that utilizes a second PPDU format different than thefirst PPDU format. In some embodiments, the first range measurementsignal exchange session is between the first communication device andone second communication device, and the second range measurement signalexchange session is also between the first communication device and theone second communication device. In some embodiments, the first rangemeasurement signal exchange session is between the first communicationdevice and one second communication device, and the second rangemeasurement signal exchange session is between the first communicationdevice and another second communication device.

In some embodiments, the plurality of range measurement signal exchangesessions include a first range measurement signal exchange sessionbetween a first communication device and one second communicationdevice, a second range measurement signal exchange session between thefirst communication device and another second communication device.

At block 708, a single packet is generated to include the schedulinginformation generated at block 704. In an embodiment, a single IE isgenerated to include the scheduling information generated at block 704,and the single packet is generated to include the single IE. Forexample, in an embodiment, the single IE has the same format asillustrated in FIG. 4. In other embodiments, the single IE has asuitable format similar to the example format illustrated in FIG. 4.

In an embodiment, the single packet is a beacon packet. In anembodiment, the single packet is a broadcast packet. In an embodiment,the single packet is a FTM response packet that is responsive to arequest packet received by the AP 14-1.

At block 712, the single packet generated at block 708 is transmitted sothat a third communication device can use the scheduling information toobserve one or more of the range measurement signal exchange sessions inthe plurality of range measurement signal exchange sessions between thefirst communication device and the one or more second communicationdevices, to determine range measurements.

As discussed above, in some embodiments, the network interface device 16is configured to implement the method 700. For example, in anembodiment, the MAC processor 18 is configured to perform block 704. Inan embodiment, the MAC processor 18 and the PHY processor 20 areconfigured to implement block 708. For example, in an embodiment, theMAC processor 18 is configured to generate a single IE that includes thescheduling information, and generate a MAC layer data unit that includesthe single IE. In an embodiment, the PHY processor 20 receives the MAClayer data unit and generates a PPDU by encapsulating the MAC layer dataunit in a PHY header. In an embodiment, the network interface device 16is configured to cause the AP 14-1 to transmit the single packet via oneor more of the antennas 24.

FIG. 8 is a flow diagram of an example method 800 for performing rangemeasurements in a wireless communication network, according to anembodiment. In some embodiments, the network interface device 27 of FIG.1 is configured to implement the method 800, and merely for ease ofexplanation, the method 800 is described with reference to FIGS. 1, 2A,2B, and 4. However, the method 800 is utilized with and/or implementedin suitable systems, devices, and/or data formats other than thosediscussed in connection with in FIGS. 1, 2A, 2B, and 4, in someembodiments.

At block 804, a single packet is received at a first communicationdevice, where the single packet includes scheduling information for aplurality of range measurement signal exchange sessions, the pluralityof range measurement signal exchange sessions involving transmission ofrange measurement signals from a second communication device to one ormore third communication devices.

In some embodiments, the plurality of range measurement signal exchangesessions include a first range measurement signal exchange session thatutilizes a first channel bandwidth, and a second range measurementsignal exchange session that utilizes a second channel bandwidthdifferent than the first channel bandwidth. In some embodiments, thefirst range measurement signal exchange session is between the secondcommunication device and one third communication device, and the secondrange measurement signal exchange session is also between the secondcommunication device and the one third communication device. In someembodiments, the first range measurement signal exchange session isbetween the second communication device and one third communicationdevice, and the second range measurement signal exchange session isbetween the second communication device and another third communicationdevice.

In some embodiments, the plurality of range measurement signal exchangesessions include a first range measurement signal exchange session thatutilizes a first PPDU format, and a second range measurement signalexchange session that utilizes a second PPDU format different than thefirst PPDU format. In some embodiments, the first range measurementsignal exchange session is between the second communication device andone third communication device, and the second range measurement signalexchange session is also between the second communication device and theone third communication device. In some embodiments, the first rangemeasurement signal exchange session is between the second communicationdevice and one third communication device, and the second rangemeasurement signal exchange session is between the second communicationdevice and another third communication device.

In some embodiments, the plurality of range measurement signal exchangesessions include a first range measurement signal exchange sessionbetween a second communication device and one third communicationdevice, a second range measurement signal exchange session between thesecond communication device and another third communication device.

In some embodiments, the single packet includes a single IE thatincludes the scheduling information discussed above. For example, in anembodiment, the single IE has the same format as illustrated in FIG. 4.In other embodiments, the single IE has a suitable format similar to theexample format illustrated in FIG. 4.

In an embodiment, the single packet is a beacon packet. In anembodiment, the single packet is a broadcast packet. In an embodiment,the single packet is a FTM response packet that is responsive to arequest packet sent by the first communication device.

At block 808, it is determined when one of the range measurement signalexchange sessions will occur based on the scheduling information in thesingle packet received at block 804. In some embodiments, it isdetermined when more than one of the range measurement signal exchangesessions will occur based on the scheduling information in the singlepacket received at block 804.

At block 812, the one range measurement signal exchange session isobserved by the first communication device responsive to determiningwhen the one range measurement signal exchange session will occur atblock 808. In some embodiments in which it is determined at block 808when more than one of the range measurement signal exchange sessionswill occur, the more than one of the range measurement signal exchangesessions are observed.

At block 816, range measurements are determined based on the one or morerange measurement signal exchange sessions observed at block 812.

In some embodiments in which the scheduling information in the singlepacket received at block 804 indicates that the one range measurementsignal exchange session uses a first channel bandwidth that is differentthan one or more second channel bandwidths used in one or more otherrange measurement signal exchange sessions in the plurality of rangemeasurement signal exchange sessions, the method 800 also includes:determining that the first communication device is capable of using thefirst channel bandwidth and is not capable of using the one or moresecond channel bandwidths; and in response to determining that the firstcommunication device is capable of using the first channel bandwidth andis not capable of using the one or more second channel bandwidths,selecting to observe the one range measurement signal exchange session.

In some embodiments in which the scheduling information in the singlepacket received at block 804 indicates that the one range measurementsignal exchange session uses a first PPDU format that is different thanone or more second PPDU formats used in one or more other rangemeasurement signal exchange sessions in the plurality of rangemeasurement signal exchange sessions, and the method 800 furtherincludes: determining, at the first communication device, that the firstcommunication device is capable of using the first PPDU format and isnot capable of using the one or more second PPDU formats; and inresponse to determining that the first communication device is capableof using the first PPDU format and is not capable of using the one ormore second PPDU formats, selecting, at the first communication device,to observe the one range measurement signal exchange session.

In some embodiments in which the scheduling information in the singlepacket received at block 804 includes first scheduling information for afirst range measurement signal exchange session between the secondcommunication device and one third communication device, and thescheduling information includes second scheduling information for asecond range measurement signal exchange session between the secondcommunication device and another third communication device, the methodincludes: determining when the first range measurement signal exchangesession will occur using the first scheduling information in the singlepacket; determining first range measurements based on observing thefirst range measurement signal exchange session; determining when thesecond range measurement signal exchange session will occur using thesecond scheduling information in the single packet; and determiningsecond range measurements based on observing the second rangemeasurement signal exchange session.

In some embodiments, the method 800 also includes transmitting a requestpacket that requests the scheduling information, and the single packetreceived at block 804 is responsive to the request packet.

As discussed above, in some embodiments, the network interface device 27is configured to implement the method 800 at least partially. Forexample, in an embodiment, the PHY processor 20 is configured to performblock 804. In an embodiment, the MAC processor 28 is configured toimplement block 808. In an embodiment, the MAC processor 28 isconfigured to control the network interface device 27 to observe therange measurement signal exchange session at block 812. In anembodiment, MAC processor 28 is configured to implement the block 812.In another embodiment, the host processor 26 is configured to implementat least a portion of the block 812.

FIG. 9 is a flow diagram of an example method 900 for facilitating rangemeasurements in a wireless communication network, according to anembodiment. In some embodiments, the network interface device 16 of FIG.1 is configured to implement the method 900, and merely for ease ofexplanation, the method 900 is described with reference to FIGS. 1, 2A,and 2B. However, the method 900 is utilized with and/or implemented insuitable systems, devices, and/or data formats other than thosediscussed in connection with in FIGS. 1, 2A, 2B, and 4, in someembodiments.

At block 904, AP1 determines that both AP1 and AP2 support an optionalset of transmission parameters comprising one or more of i) a rate, ii)an MCS, iii) a number of spatial streams, and/or iv) a combination of a)an MCS and b) a number of spatial streams that are not in a mandatoryset of transmission parameters including i) rates, ii) MCSs, iii)numbers of spatial streams, and/or iv) mandatory combinations of a) MCSsand b) numbers of spatial streams that are defined as mandatory by acommunication protocol for a particular PPDU format. For example, in anembodiment, AP1 and AP2 exchange packets that capabilities of AP1 andAP2 with regard to rates, MCSs, numbers of spatial streams, etc.

At block 908, AP1 determines that channel conditions support using oneor more parameters from the optional set when transmitting to AP2.

At block 912, even though channel conditions would support AP1transmitting range measurement packet with the particular PPDU formatusing one or more parameters from the optional set, AP1 uses onlyparameters from the mandatory set to transmit range measurement packetsto AP2 to ensure that observing stations capable of using the particularPPDU format are able to observe the range measurement signals.

Thus, in some embodiments, the AP1 is restricted to using, whentransmitting FTM packets according to a particular PPDU format, one ormore of i) a mandatory rate, ii) a mandatory MCS, and/or iii) amandatory combination of a) an MCS, and b) a number of spatial streams,for the particular PPDU format, as specified by the communicationprotocol.

As discussed above, in some embodiments, the network interface device 16is configured to implement the method 900. For example, in anembodiment, the MAC processor 18 is configured to perform blocks 904 and908. In an embodiment, the MAC processor 18 and the PHY processor 20 areconfigured to implement block 912. For example, in an embodiment, theMAC processor 18 is configured to select transmission parameters to beused by the PHY processor 20. In an embodiment, the PHY processor 20receives the MAC layer data units and indications of the transmissionparameters that are to be used, and generates PPDUs by encapsulating theMAC layer data units in respective PHY headers. In an embodiment, thenetwork interface device 16 is configured to cause the AP 14-1 totransmit the PPDUs via one or more of the antennas 24.

At least some of the various blocks, operations, and techniquesdescribed above may be implemented utilizing hardware, a processorexecuting firmware instructions, a processor executing softwareinstructions, or any combination thereof. When implemented utilizing aprocessor executing software or firmware instructions, the software orfirmware instructions may be stored in any computer readable memory suchas on a magnetic disk, an optical disk, or other storage medium, in aRAM or ROM or flash memory, processor, hard disk drive, optical diskdrive, tape drive, etc. The software or firmware instructions mayinclude machine readable instructions that, when executed by one or moreprocessors, cause the one or more processors to perform various acts.

When implemented in hardware, the hardware may comprise one or more ofdiscrete components, an integrated circuit, an application-specificintegrated circuit (ASIC), a programmable logic device (PLD), etc.

While the present invention has been described with reference tospecific examples, which are intended to be illustrative only and not tobe limiting of the invention, changes, additions and/or deletions may bemade to the disclosed embodiments without departing from the scope ofthe invention.

What is claimed is:
 1. A method, comprising: determining, at a firstcommunication device, scheduling information for a plurality of rangemeasurement signal exchange sessions that will occur in the futurebetween the first communication device and one or more secondcommunication devices, wherein the plurality of range measurement signalexchange sessions involve using i) different channel bandwidths, and ii)different physical layer data unit (PPDU) formats for the plurality ofrange measurement signal exchange sessions, and wherein the schedulinginformation includes, for each session, i) a respective indication ofwhen the session will occur in the future, ii) a respective indicationof a respective channel bandwidth, selected from a set of multipledifferent channel bandwidths, that will be used during the session inthe future, and iii) a respective indication of a respective PPDUformat, selected from a set of multiple different PPDU formats definedby different communication protocols, that will be used during thesession in the future; generating, at the first communication device, asingle packet that includes the scheduling information, the singlepacket including, for each second communication device with which thefirst communication device will exchange signals during one or morerange measurement signal exchange sessions in the future, a respectivefield specifying parameters for the one or more range measurement signalexchange sessions between the first communication device and therespective second communication device; and transmitting, with the firstcommunication device, the single packet so that a third communicationdevice can use the scheduling information to observe, in the future, oneor more of the range measurement signal exchange sessions in theplurality of range measurement signal exchange sessions between thefirst communication device and one or more second communication devices,to determine range measurements.
 2. The method of claim 1, wherein:determining the scheduling information includes determining firstscheduling information for a first range measurement signal exchangesession that will occur in the future between the first communicationdevice and one second communication device, and determining secondscheduling information for a second range measurement signal exchangesession that will occur in the future between the first communicationdevice and another second communication device; and generating thesingle packet comprises generating the single packet to include thefirst scheduling information and the second scheduling information. 3.The method of claim 1, wherein: determining the scheduling informationincludes determining first scheduling information for a first rangemeasurement signal exchange session that will occur in the futurebetween the first communication device and one second communicationdevice, wherein the first range measurement signal exchange sessioninvolves using at least one of i) a first channel bandwidth, and ii) afirst PPDU format, and determining second scheduling information for asecond range measurement signal exchange session that will occur in thefuture between the first communication device and the one secondcommunication device, wherein the second range measurement signalexchange session involves using at least one of i) a second channelbandwidth different than the first channel bandwidth, and ii) a secondPPDU format different than the first PPDU format; and generating thesingle packet comprises generating the single packet to include thefirst scheduling information and the second scheduling information. 4.The method of claim 1, further comprising: generating, at the firstcommunication device, a single information element that includes thescheduling information, wherein generating the single packet comprisesgenerating the single packet to include the single information element.5. The method of claim 1, wherein: generating the single packetcomprises generating a single beacon frame to include the schedulinginformation.
 6. The method of claim 1, further comprising: generating,at the first communication device, one or more range measurement signalpackets according to a first PPDU format defined by a communicationprotocol; transmitting, from the first communication device to thesecond communication device, the one or more range measurement signalpackets according to one or more of i) a mandatory rate, ii) a mandatorymodulation and coding scheme (MCS), iii) a mandatory number of spatialstreams, and iv) a mandatory combination of a) an MCS and b) a number ofspatial streams defined by the communication protocol even when i) thefirst communication device and the second communication device supporttwo or more of a) a non-mandatory rate, b) a non-mandatory MCS, and c) anon-mandatory number of spatial streams defined by the communicationprotocol, and ii) channel conditions between the first communicationdevice and the second communication device support using two or more ofa) the non-mandatory rate, b) the non-mandatory MCS, and c) thenon-mandatory number of spatial streams, wherein transmitting the one ormore range measurement signal packets to the second communication deviceaccording to the one or more of i) the mandatory rate, ii) the mandatoryMCS, iii) the mandatory number of spatial streams, and iv) the mandatorycombination of a) a MCS and b) a number of spatial streams, supportsobservation of the one or more range measurement signal packets by thethird communication device.
 7. The method of claim 1, wherein: therespective field includes (i) a first portion specifying a plurality offirst parameters common to the one or more range measurement signalexchange sessions that will occur between the first communication deviceand the respective second communication device, and (ii) a respectivesecond portion corresponding to a respective one of the one or morerange measurement signal exchange sessions that will occur between thefirst communication device and the respective second communicationdevice, each second portion including a plurality of second parametersspecific to the corresponding range measurement signal exchange session,the plurality of second parameters including a) the respectiveindication of the channel bandwidth, and b) the respective indication ofthe PPDU format.
 8. An apparatus, comprising: a network interface deviceassociated with a first communication device, wherein the networkinterface device includes one or more integrated circuits (ICs)configured to determine scheduling information for a plurality of rangemeasurement signal exchange sessions that will occur in the futurebetween the first communication device and one or more secondcommunication devices, wherein the plurality of range measurement signalexchange sessions involve using i) different channel bandwidths, and ii)different physical layer data unit (PPDU) formats for the plurality ofrange measurement signal exchange sessions, and wherein the schedulinginformation includes, for each session, i) a respective indication ofwhen the session will occur in the future, ii) a respective indicationof a respective channel bandwidth, selected from a set of multipledifferent channel bandwidths, that will be used during the session inthe future, and iii) a respective indication of a respective PPDUformat, selected from a set of multiple different PPDU formats definedby different communication protocols, that will be used during thesession in the future, generate a single packet that includes thescheduling information, the single packet including, for each secondcommunication device with which the first communication device willexchange signals during one or more range measurement signal exchangesessions in the future, a respective field specifying parameters for theone or more range measurement signal exchange sessions between the firstcommunication device and the respective second communication device, andcause the first communication device to transmit the single packet sothat a third communication device can use the scheduling information toobserve, in the future, one or more of the range measurement signalexchange sessions in the plurality of range measurement signal exchangesessions between the first communication device and one or more secondcommunication devices, to determine range measurements.
 9. The apparatusof claim 8, wherein the one or more ICs are configured to: determinefirst scheduling information for a first range measurement signalexchange session that will occur in the future between the firstcommunication device and one second communication device, determinesecond scheduling information for a second range measurement signalexchange session that will occur in the future between the firstcommunication device and another second communication device, andgenerate the single packet to include the first scheduling informationand the second scheduling information.
 10. The apparatus of claim 8,wherein the one or more ICs are configured to: determine firstscheduling information for a first range measurement signal exchangesession that will occur in the future between the first communicationdevice and one second communication device, wherein the first rangemeasurement signal exchange session involves using at least one of i) afirst channel bandwidth, and ii) a first PPDU format, determine secondscheduling information for a second range measurement signal exchangesession that will occur in the future between the first communicationdevice and the one second communication device, wherein the second rangemeasurement signal exchange session involves using at least one of i) asecond channel bandwidth different than the first channel bandwidth, andii) a second PPDU format different than the first PPDU format, andgenerate the single packet to include the first scheduling informationand the second scheduling information.
 11. The apparatus of claim 8,wherein the one or more ICs are configured to: generate a singleinformation element that includes the scheduling information, andgenerate the single packet to include the single information element.12. The apparatus of claim 8, wherein the one or more ICs are configuredgenerate the single packet as a single beacon frame that includes thescheduling information.
 13. The apparatus of claim 8, wherein the one ormore ICs are configured to: generate one or more range measurementsignal packets according to a first PPDU format defined by acommunication protocol; cause the first communication device totransmit, to the second communication device, the one or more rangemeasurement signal packets according to one or more of i) a mandatoryrate, ii) a mandatory modulation and coding scheme (MCS), iii) amandatory number of spatial streams, and iv) a mandatory combination ofa) an MCS and b) a number of spatial streams defined by thecommunication protocol even when i) the first communication device andthe second communication device support two or more of a) anon-mandatory rate, b) a non-mandatory MCS, and c) a non-mandatorynumber of spatial streams defined by the communication protocol, and ii)channel conditions between the first communication device and the secondcommunication device support using two or more of a) the non-mandatoryrate, b) the non-mandatory MCS, and c) the non-mandatory number ofspatial streams, wherein transmitting the one or more range measurementsignal packets to the second communication device according to the oneor more of i) the mandatory rate, ii) the mandatory MCS, iii) themandatory number of spatial streams, and iv) the mandatory combinationof a) a MCS and b) a number of spatial streams, supports observation ofthe one or more range measurement signal packets by the thirdcommunication device.
 14. The apparatus of claim 8, wherein: therespective field includes (i) a first portion specifying a plurality offirst parameters common to the one or more range measurement signalexchange sessions that will occur between the first communication deviceand the respective second communication device, and (ii) a respectivesecond portion corresponding to a respective one of the one or morerange measurement signal exchange sessions that will occur between thefirst communication device and the respective second communicationdevice, each second portion including a plurality of second parametersspecific to the corresponding range measurement signal exchange session,the plurality of second parameters including a) the respectiveindication of the channel bandwidth, and b) the respective indication ofthe PPDU format.
 15. A method, comprising: receiving, at a firstcommunication device, a single packet that includes schedulinginformation for a plurality of range measurement signal exchangesessions that will occur in the future between a second communicationdevice and one or more third communication devices, wherein theplurality of range measurement signal exchange sessions involve using i)different channel bandwidths, and ii) different physical layer data unit(PPDU) formats for the plurality of range measurement signal exchangesessions, and wherein the scheduling information includes, for eachsession, i) a respective indication of when the session will occur inthe future, ii) a respective indication of a respective channelbandwidth, selected from a set of multiple different channel bandwidths,that will be used during the session in the future, and iii) arespective indication of a respective PPDU format, selected from a setof multiple different PPDU formats defined by different communicationprotocols, that will be used during the session in the future, whereinthe single packet includes, for each third communication device withwhich the second communication device will exchange signals during oneor more range measurement signal exchange sessions in the future, arespective field specifying parameters for the one or more rangemeasurement signal exchange sessions between the second communicationdevice and the respective third communication device; determining, atthe first communication device when one of the range measurement signalexchange sessions will occur in the future between the secondcommunication device and the one or more third communication devicesusing the scheduling information in the single packet; in response todetermining when the one range measurement signal exchange session willoccur using the scheduling information in the single packet, observing,with the first communication device, the one range measurement signalexchange session between the second communication device and the one ormore third communication devices; and determining, at the firstcommunication device, range measurements based on observing the onerange measurement signal exchange session between the secondcommunication device and the one or more third communication devices.16. The method of claim 15, wherein: the scheduling informationindicates that the one range measurement signal exchange session thatwill occur in the future between the second communication device and theone or more third communication devices involves using a first channelbandwidth that is different than one or more second channel bandwidthsthat will be used in one or more other range measurement signal exchangesessions that will occur in the future between the second communicationdevice and the one or more third communication devices in the pluralityof range measurement signal exchange sessions; determining, at the firstcommunication device, that the first communication device is capable ofusing the first channel bandwidth and is not capable of using the one ormore second channel bandwidths; and in response to determining that thefirst communication device is capable of using the first channelbandwidth and is not capable of using the one or more second channelbandwidths, selecting, at the first communication device, to observe theone range measurement signal exchange session that will occur in thefuture between the second communication device and the one or more thirdcommunication devices.
 17. The method of claim 15, wherein: thescheduling information indicates that the one range measurement signalexchange session that will occur in the future between the secondcommunication device and the one or more third communication devicesinvolves using a first PPDU format that is different than one or moresecond PPDU formats that will be used in one or more other rangemeasurement signal exchange sessions that will occur in the futurebetween the second communication device and the one or more thirdcommunication devices in the plurality of range measurement signalexchange sessions; determining, at the first communication device, thatthe first communication device is capable of using the first PPDU formatand is not capable of using the one or more second PPDU formats; and inresponse to determining that the first communication device is capableof using the first PPDU format and is not capable of using the one ormore second PPDU formats, selecting, at the first communication device,to observe the one range measurement signal exchange session that willoccur in the future between the second communication device and the oneor more third communication devices.
 18. The method of claim 15,wherein: the scheduling information includes first schedulinginformation for a first range measurement signal exchange session thatwill occur in the future between the second communication device and onethird communication device; the scheduling information includes secondscheduling information for a second range measurement signal exchangesession that will occur in the future between the second communicationdevice and another third communication device; and wherein determiningwhen the one range measurement signal exchange session will occur in thefuture comprises determining when the first range measurement signalexchange session will occur in the future using the first schedulinginformation in the single packet; determining range measurements basedon observing the one range measurement signal exchange session comprisesdetermining first range measurements based on observing the first rangemeasurement signal exchange session between the second communicationdevice and the one third communication device; and the method furthercomprises: determining, at the first communication device, when thesecond range measurement signal exchange session will occur in thefuture using the second scheduling information in the single packet, anddetermining, at the first communication device, second rangemeasurements based on observing the second range measurement signalexchange session between the second communication device and the otherthird communication device.
 19. The method of claim 15, furthercomprising: transmitting, with the first communication device, a requestpacket that requests the scheduling information, wherein the singlepacket that includes the scheduling information is responsive to therequest packet.
 20. The method of claim 15, wherein: the respectivefield includes (i) a first portion specifying a plurality of firstparameters common to the one or more range measurement signal exchangesessions that will occur between the second communication device and therespective third communication device, and (ii) a respective secondportion corresponding to a respective one of the one or more rangemeasurement signal exchange sessions that will occur between the secondcommunication device and the respective third communication device, eachsecond portion including a plurality of second parameters specific tothe corresponding range measurement signal exchange session, theplurality of second parameters including a) the respective indication ofthe channel bandwidth, and b) the respective indication of the PPDUformat.
 21. An apparatus, comprising: a network interface deviceassociated with a first communication device, wherein the networkinterface device includes one or more integrated circuits (ICs)configured to receive a single packet that includes schedulinginformation for a plurality of range measurement signal exchangesessions that will occur in the future between a second communicationdevice and one or more third communication devices, wherein theplurality of range measurement signal exchange sessions involve using i)different channel bandwidths, and ii) different physical layer data unit(PPDU) formats for the plurality of range measurement signal exchangesessions, and wherein the scheduling information includes, for eachsession, i) a respective indication of when the session will occur inthe future, ii) a respective indication of a respective channelbandwidth, selected from a set of multiple different channel bandwidths,that will be used during the session in the future, and iii) arespective indication of a respective PPDU format, selected from a setof multiple different PPDU formats defined by different communicationprotocols, that will be used during the session in the future, whereinthe single packet includes, for each third communication device withwhich the second communication device will exchange signals during oneor more range measurement signal exchange sessions in the future, arespective field specifying parameters for the one or more rangemeasurement signal exchange sessions between the second communicationdevice and the respective third communication device, determine when oneof the range measurement signal exchange sessions will occur in thefuture between the second communication device and the one or more thirdcommunication devices using the scheduling information in the singlepacket, in response to determining when the one range measurement signalexchange session will occur using the scheduling information in thesingle packet, observe the one range measurement signal exchange sessionbetween the second communication device and the one or more thirdcommunication devices, and determine range measurements based onobserving the one range measurement signal exchange session between thesecond communication device and the one or more third communicationdevices.
 22. The apparatus of claim 21, wherein: the schedulinginformation indicates that the one range measurement signal exchangesession that will occur in the future between the second communicationdevice and the one or more third communication devices involves using afirst channel bandwidth that is different than one or more secondchannel bandwidths that will be used in one or more other rangemeasurement signal exchange sessions that will occur in the futurebetween the second communication device and the one or more thirdcommunication devices in the plurality of range measurement signalexchange sessions; the one or more ICs are configured to determine thatthe first communication device is capable of using the first channelbandwidth and is not capable of using the one or more second channelbandwidths; and the one or more ICs are configured to: in response todetermining that the first communication device is capable of using thefirst channel bandwidth and is not capable of using the one or moresecond channel bandwidths, selecting to observe the one rangemeasurement signal exchange session that will occur in the futurebetween the second communication device and the one or more thirdcommunication devices.
 23. The apparatus of claim 21, wherein: thescheduling information indicates that the one range measurement signalexchange session that will occur in the future between the secondcommunication device and the one or more third communication devicesinvolves using a first PPDU format that is different than one or moresecond PPDU formats that will be used in one or more other rangemeasurement signal exchange sessions that will occur in the futurebetween the second communication device and the one or more thirdcommunication devices in the plurality of range measurement signalexchange sessions; the one or more ICs are configured to determine thatthe first communication device is capable of using the first PPDU formatand is not capable of using the one or more second PPDU formats; and theone or more ICs are configured to: in response to determining that thefirst communication device is capable of using the first PPDU format andis not capable of using the one or more second PPDU formats, select toobserve the one range measurement signal exchange session that willoccur in the future between the second communication device and the oneor more third communication devices.
 24. The apparatus of claim 21,wherein: the scheduling information includes first schedulinginformation for a first range measurement signal exchange session thatwill occur in the future between the second communication device and onethird communication device; the scheduling information includes secondscheduling information for a second range measurement signal exchangesession that will occur in the future between the second communicationdevice and another third communication device; and the one rangemeasurement signal exchange session that will occur in the future is thefirst range measurement signal exchange session that will occur in thefuture determined using the first scheduling information in the singlepacket; the determined range measurements are first range measurementsdetermined based on observing the first range measurement signalexchange session between the second communication device and the onethird communication device; and the one or more ICs are configured to:determine when the second range measurement signal exchange session willoccur in the future using the second scheduling information in thesingle packet, and determine second range measurements based onobserving the second range measurement signal exchange session betweenthe second communication device and the other third communicationdevice.
 25. The apparatus of claim 21, wherein the one or more ICs areconfigured to: cause the first communication device to transmit arequest packet that requests the scheduling information, wherein thesingle packet that includes the scheduling information is responsive tothe request packet.
 26. The apparatus of claim 21, wherein: therespective field includes (i) a first portion specifying a plurality offirst parameters common to the one or more range measurement signalexchange sessions that will occur between the second communicationdevice and the respective third communication device, and (ii) arespective second portion corresponding to a respective one of the oneor more range measurement signal exchange sessions that will occurbetween the second communication device and the respective thirdcommunication device, each second portion including a plurality ofsecond parameters specific to the corresponding range measurement signalexchange session, the plurality of second parameters including a) therespective indication of the channel bandwidth, and b) the respectiveindication of the PPDU format.